Organization of the region encompassing the human serum amyloid A (SAA) gene family on chromosome 11p15.1.

The four members of the human serum amyloid A protein (SAA) gene family are clustered on human chromosome 11p15.1. Three genes are differentially expressed and encode small apolipoproteins of M(r) 12-19 kDa: SAA1 and SAA2 encode the acute phase SAAs (A-SAAs), and SAA4 encodes the constitutively expressed SAA (C-SAA). A fourth locus, SAA3, is a pseudogene. The human SAA gene family encompasses approximately 150 kb contained on a 900-kb yeast artificial chromosome contig. SAA1 and SAA2 are 15-20 kb apart and are arranged in divergent transcriptional orientations. SAA4 is 9 kb downstream of SAA2 and in the same orientation. SAA3 is 110 kb downstream of SAA4, and its relative orientation could not be determined. All genes known to be in the same human and mouse syntenic linkage group as SAA were mapped within the contig. Interphase FISH was used to orientate the region relative to the centromere: cen-LDHC-LDHA-SAA1-SAA2-SAA4-SAA3-TP H-D11S18- KCNC1-MYOD1-pter.